Adhesives are used in a variety of environments for a variety of applications. Such environments and applications require adhesives to have specific temperature profiles, viscosity profiles, chemical and flammable resistant profiles, and adhesion characteristics. Known adhesives do not adequately meet all of these requirements.
In wiring applications, adhesives can be used with fluoropolymers. Fluoropolymers have low surface energy, for example, below 25 dynes/cm. This low surface energy makes it difficult for an adhesive to bond to the fluoropolymer. Surface treatments can ameliorate this; however, surface treatments present other problems and are often not available in repair conditions. For example, chemical etching or high energy plasma treatment can be used to activate a fluoropolymer surface. However, etching chemicals (such as sodium naphthalene) cannot be used in a repair area due to the toxicity and flammability. Also, plasma equipment is not able to be used due to the crowded nature of a repair area.
Polytetrafluoroethylene surfaces can be especially difficult for adhesion. Certain polymeric materials are unable to diffuse into the surface, thereby resulting in a lack of adhesion. Polymeric materials that are able to diffuse into the surface may not have desired properties. For example, such materials may drip and/or have melting points being below a maximum service temperature.
Current adhesives do not desirably bond to polytetrafluoroethylene (PTFE). Positioning current adhesives in contact with a surface having PTFE creates a microgap and/or delamination between the adhesive and the PTFE surface.
Certain polymers can provide adhesion to fluoropolymers by having similar chemical structures, relatively low surface energies, and low melting points. Such polymers can have desirable flow and wet-ability on the fluoropolymers. However, such low melting temperatures result in dripping issues in high service temperature applications, such as aerospace applications. The dripping issues can cause seal failure.
Other fluoropolymers can provide adhesion to PTFE surfaces when the PTFE surfaces are etched, have an acid application, and/or are otherwise surface-modified. Such limitations render PTFE surfaces difficult to repair. In addition, such surface modifications can be undesirable by relying upon expensive or environmentally-unfriendly chemicals.
An adhesive manufacturing process, an adhesive, and article having an adhesive that do not suffer from one or more of the above drawbacks would be desirable in the art.